Last month, Pete Wehner, a White House strategist, sent journalists an e-mail drawing attention to a statement by John F. Kennedy—then still Sen. Kennedy—in 1959: "I believe if we can hold out for the long run there will be sufficient evolutionary changes in the Communistic system in Russia as well as in China to give us some hope of success. The 'magic power' on our side is the desire of every person to be free, of every nation to be independent.... It is because I believe our system is more in keeping with the fundamentals of human nature that I believe we are ultimately going to be successful, provided we have sufficient self-discipline and perseverance to maintain our own strength through a long, testing period."

Kennedy's statement, Wehner commented, "is an articulate explanation of what is at the core of President Bush's Freedom Agenda. And his answer is a reminder of how much things have changed among liberals, who once embraced the foreign-policy idealism (anchored in the design of human nature) of Franklin Roosevelt, Harry Truman, and John F. Kennedy."

It is true that the United States would do well to recall and learn from President Kennedy. But which President Kennedy? The idealist who made the speeches, or the realist who made the decisions?

The idealist was the JFK of the 1961 Inaugural Address, whose clarion rhetoric—"We shall pay any price, bear any burden ... to assure the survival and the success of liberty"—leads in a straight line to President Bush's second Inaugural Address: "The best hope for peace in our world is the expansion of freedom in all the world.... So it is the policy of the United States to seek and support the growth of democratic movements and institutions in every nation and culture, with the ultimate goal of ending tyranny in our world."

The rhetorical kinship is evident (and not coincidental). But look more closely. Bush's call to end tyranny everywhere is revolutionary in scope and ambition. It proposes not just to make the world safe for democracy but to make the whole world safely democratic.

Kennedy, by contrast, promised to "bear any burden" to defend the free world against communism—not to free the whole world. And notice, in JFK's 1959 remark, the telling qualifications: "If we can hold out for the long run there will be sufficient evolutionary changes ... to give us some hope of success."

Kennedy was no revolutionary in foreign policy. Indeed, he was contemptuous of idealistic reformers. Meeting on August 20, 1962, with his senior foreign-policy advisers, he read from a draft document describing a national counterinsurgency strategy. The United States, said Kennedy, reading aloud, seeks "to insure that modernization of the local society evolves in directions which will afford a congenial world environment for fruitful international cooperation and our ... for our way of life."

Kennedy's comment: "That's a lot of crap."

Continuing with a boilerplate passage about promoting free markets, JFK remarks, "We're not really fighting for the private enterprise system." Then he coldly concludes, "I thought this was a rather amateurish paper." (The transcript is available at www.whitehousetapes.org.)

In the golden haze of his speeches, one too easily forgets that JFK the practitioner was a hard-boiled realist. So were Presidents Eisenhower, Nixon, George H.W. Bush, and, for the most part, FDR and Truman.

For 30 years, nonetheless, realism has been in bad odor. Liberals have scorned it for betraying human rights and drawing the country into Vietnam (though whether the flinty-eyed JFK would have embarked on LBJ's massive escalation in Indochina is questionable). Conservatives have scorned it for tolerating communism (though containment ultimately brought down the Soviet Union).

Ironically, the one presidential nominee in recent times to campaign explicitly as a realist was George W. Bush, who in 2000 derided "nation building" as tangential to U.S. interests and rejected as "arrogance" the notion that America should reform the world. But the realist revival was brief. Bush soon converted to the Bush Doctrine, which seeks to make the world peaceful by making it free.

Centrist Democrats argue that Bush's pro-democracy policy is, if anything, not ambitious or aggressive enough. In a thoughtful new collection of essays (With All Our Might: A Progressive Strategy for Defeating Jihadism and Defending Liberty), centrist Democratic strategists criticize Bush for failing to "launch a sweeping program of economic, political, and social reform" in the greater Middle East. They call for "transformative reform of virtually every sector of life" there. They rebuke "a new generation of self-described 'realists' from both the Left and Right [who] argue that the efforts to confront tyranny and promote democracy have been a fool's errand."

Lacking mainstream advocacy, realism has indeed fallen into the hands of cranks on the left and the right, who propound bastardized versions—the Far Left out of pacifism and hatred of Bush, the Far Right out of isolationism and cultural chauvinism. The pity is that no one in public life is making the respectable case for what is an eminently respectable doctrine.

Or, really, a respectable attitude. Realism is not so much a doctrine, aspiration, or policy as a sense of how the world works. Properly understood, it does not define U.S. interests narrowly or cynically, dismiss human rights as sissy stuff, or espouse indifference to regimes' internal structure. The essence of realism, rather, is seeing the world as it is, not as we wish it to be. Specifically, realism understands that:

U.S. influence is a limited resource that needs conservation, and that using it requires leaders to make distasteful trade-offs and to deal with bad guys.

Because human beings are not easily governable and because chaos is a first-order strategic menace, stability should be a top-tier priority, never a mere afterthought.

However idealistic its self-image, America has too many status quo interests ever to be a revolutionary power.

Except in the short run, the American people care more about interests than ideals and will tolerate idealistic adventurism only briefly.

Realism does not imply giving up on democratic reform or noble ambitions. It does imply pursuing revolutionary goals on a geological time scale. The Cold War, a classic instance, spanned five decades. It was counter-revolutionary rather than revolutionary in nature. It was primarily anti-communist, not pro-democratic. And, as conservatives often complained, it was a "let burn" policy toward communism, not a policy of extinguishment.

Human rights? Important, of course; that is a lesson that realists have taken on board since President Carter. But human rights are not well served by hostile regimes or by anarchy. In Iraq, where neoconservatives hope to implant a model government, realists would settle for a stable and friendly government that might have to set aside some democratic scruples. Iraq may wind up needing to look like Jordan or Egypt in order not to look like Lebanon in the 1980s, Bosnia in the 1990s, or today's Palestine or Iran.

Freedom? Democracy? Also important—of course! But even if it is true that "eventually the call of freedom comes to every mind and every soul," as Bush declared in his second inaugural, "eventually" is a long time. More to the point, many people who desire freedom for themselves do not also desire it for others—a fact that realists bear in mind when told that democracy is itching to burst out all over.

The rap on realism is that the emphasis on stability turned the Middle East into an incubator of radicalism and of violence for export. It's a fair rap, but the realist response is recalibration, not revolution. Elections brought Islamist radicals to power in Iran and Palestine and might well do so in Egypt if held today. The U.S. should not prop up Hosni Mubarak indefinitely, but neither should it knock him over. Jeanne Kirkpatrick, who was U.N. ambassador in the Reagan administration, was right when she warned back in 1979 that replacing a friendly status quo dictatorship with an unfriendly radical dictatorship serves neither American interests nor American ideals.

From a realist point of view, neoconservatives and unilateralists are too aggressive, isolationists and pacifists too passive, idealists and moralists too scrupulous, and Wilsonian reformers too destabilizing. Realists can be criticized for not proffering a specific agenda of their own, and that, too, is a fair rap. Realism does not define, and should not limit, America's aims in the world.

It is, however, an indispensable ingredient of a grown-up foreign policy. If realism had the advocacy it deserves, it would be enjoying a renaissance it has earned.